The present invention relates generally to analog-to-digital converters and self calibration algorithms, and more particularly, to autocalibration circuitry and algorithm for aligning interstage gain in a high resolution multipass analog-to-digital converter.
Prior art relating to the present invention include U.S. Pat. No. 4,947,168 entitled "Subranging Analog-to-Digital Converter with Calibration, assigned to the assignee of the present invention. This analog-to-digital converter requires external precision references and analog multiplexers, programmable micro-controller function with memory. Also, the technique interrupts the analog-to-digital conversion process requiring a dedicated calibration time during which normal converter operation is suspended.
U.S. Pat. No. 4,399,426 entitled "On Board Self-Calibration of Analog-to-Digital and Digital-to-Analog Converters" discloses charge-redistributed circuit implementations of analog-to-digital converters, and does not address interstage gain alignment addressed by the present invention. U.S. Pat. No. 4,996,530 entitled "Statistically Based Continuous Autocalibration Method and Apparatus" discloses autocalibration of subranging analog-to-digital converters internal digital-to-analog-converter and does not address autocalibration of the interstage gain error.
Accordingly, it is an objective of the present invention to provide for autocalibration circuitry and algorithm for aligning interstage gain in a high resolution multipass analog-to-digital converter.